1. Field of the Invention
Devices consistent with the present invention relate to guidewires for catheters and, more particularly, to guidewires for use with low profile embolic protection devices deployed without the need for actuating delivery catheters.
2. Description of the Related Art
Arteriosclerosis, also known as atherosclerosis, is a common human ailment arising from the deposition of fatty-like substances, referred to as atheroma or plaque, on the walls of blood vessels. Such deposits occur in peripheral blood vessels that feed limbs of the body, coronary blood vessels that feed the heart, and in carotid blood vessels that feed the head, neck, and brain. Localized accumulation of deposits within regions of the blood vessels may result in stenosis, or narrowing of the vascular channel. When this occurs, blood flow is restricted and the person's health is at serious risk.
Numerous approaches for reducing and removing such vascular deposits have been proposed, including balloon angioplasty, in which a balloon-tipped catheter is used to dilate a stenosed region within the blood vessel; atherectomy, in which a blade or other cutting element is used to sever and remove the stenotic material; laser angioplasty, in which laser energy is used to ablate at least a portion of the stenotic material; and the like. Related art angioplasty catheters are well known for their utility in treating the build-up of plaque and other occlusions in blood vessels.
In order to facilitate the use of the various treatment devices, a related art guidewire is typically used to assist in moving these devices throughout the vasculature. The related art guidewire is thinner and more flexible than the deployment or retrieval catheters for the treatment devices. Therefore, the related art guidewire may more easily be manipulated through narrow or otherwise tortuous regions of the vasculature to reach the treatment area. The related art guidewire also provides a means for deploying an embolic protection device, i.e., a filter, downstream of the vasculature to filter any plaque or other occluded material which may become dislodged during treatment, and thus prevents the occlusion material from traveling through the blood vessels and becoming lodged in the brain or other smaller blood vessels preventing blood flow and causing a stroke or other damage. U.S. Pat. No. 6,336,934, which is herein incorporated by reference in its entirety, describes examples of such a related art procedure and example of the embolic protection devices.
Turning to FIGS. 1-5, the deployment of an embolic protection device using a related art guidewire is shown. As shown in FIGS. 1 and 2, the embolic protection device includes an arrangement of spokes 25 covered with a membrane or porous fabric or mesh 30 that can be folded down into a delivery sheath or pod for subsequent deployment in a target vessel. The design consists of a guidewire 10 onto which are radially or circumferentially bonded a series of pre-shaped wires 25. The wires 25 are joined on the proximal end into a movable collar or tube 15 mounted on the guidewire 10 and at the distal end into a tube 20 which is fixed to the guidewire 10. The tube 15 can move proximally and distally to the extent that it will open and close the assembly in a manner similar to an umbrella and thereby occlude the vessel, as shown in FIG. 2.
When the assembly is configured longitudinally a sheath or pod may be slid over it to cover it. A loaded catheter is positioned in a treatment area by threading it over the guidewire 10. Once the desired treatment area has been reached, the sheath may be moved back and allow the assembly be exposed in the vessel. As shown in FIGS. 3-5, an actuating sleeve 40 can then be moved forward to open or deploy the assembly. The relative sizing and choice of materials operates such that the actuating sleeve 40 will not slide on the guidewire 10 unless an external force is applied to move it. When deployed, the device will remain open and catch whatever embolic material is dislodged during treatment. At the end of the procedure, a pre-shaped component is advanced over the guidewire 10 and docks with the movable tube 15, allowing it to be slid towards the proximal end of the device with the result that the structure is closed. A larger sheath can then separately be advanced to the site of the filter and the filter may be pulled or manipulated proximally into it. When withdrawn into the sheath or catheter, the device may then be removed either over the guidewire 10 or with it.
The above related art guidewire has a number of disadvantages. First, advancements in the fabrication and use of embolic protection devices have resulted in embolic protection devices of extremely low profiles. This makes using an actuation sheath difficult. Moreover, it is desirable to be able to use an embolic protection device without the need for an actuating delivery catheter.